[Info-vax] DCL, was: Re: Microkernel

[Simon Clubley]

On 2012-08-12, FrankS <sapienza at noesys.com> wrote:
> At the risk of taking this thread even further off into tangents unknown,
> could someone explain the BENEFIT of being able to recall commands from past
> sessions?  It seems like a lot of work to implement (BASH or DCL) and I can't
> remember any time I needed to recall a command from a prior session that I
> couldn't retype from scratch.  I mean, really, how complicated are the command
> lines you're building?
>

It's not only the length of the commands, but also having quick and easy
ways of recalling them and constructing them. In bash, you can type Ctrl-R
followed by a few characters and keep hitting Ctrl-R until the matching
command is found. Tab completion makes it very easy to construct long
command lines as well.

This means that instead of having lots of little files floating around
with one line commands in them, it's _much_ easier to use the command
history file to hold the commands.

Generally, when I am working on something, I work on it for more than one
day. I also have a series of commands I use on a regular basis. In either
case, I can just type a few characters per command the next day and have
the command available once again.

Using a command history file is self maintaining as well. When I have not
used the commands for a while, they will automatically be removed from
the history file without me having to delete anything.

You asked for some example commands. I cannot discuss anything I am doing
at work, but below are some examples from home. I am currently doing some
work on a USB device stack of mine and it's very easy to find the related
sets of commands and PDF documents when I pick it up the next evening.
[I have a large (but organised) reference library and with tab completion
it's as quick to find a document from the command line as it is to use
a GUI browser, especially when you can recall the command and use it to
find related documents or use locate or find on the reference library
tree.]

stty -F /dev/ttyS3 raw -echo time 60 min 0 -crtscts -hupcl

xpdf /reflib/arm_arch_docs/cpu_docs/arm7dtmi/atmel/doc6175_AT91SAM7S_DS.pdf &

The following command is one command; I've broken it into several lines.
There are also variants for burning to flash and for different images.
There are also related commands for running ddd (and specifying the
required gdb backend) on the command line. It's _very_ easy to recall
one of these variants the next day with a few characters.

FNAME=/sd/arm-test/usb-dev-h256/usb-dev-h256_sram.bin
	/projs2/embedded/exe-openocd-0.4.0/bin/openocd
	-f /sd/simuclib/scripts/arm/sam7s256/openocd-pp-ram-run.cmd

>Generally speaking, for my purposes, command recall more than a dozen or so
> commands back in the current session has been unnecessary.  And even then I'm
> just being too lazy to type it in again.

With a permanent command history, easy recall of commands ($ recall/search
does _NOT_ qualify as easy recall) and tab completion of filenames, it's
something I really miss even on repeated short commands when it's not
available. If it's anything more complicated than viewing a file in the
current directory, it's quicker to get it from the command history under
bash.

Simon.

-- 
Simon Clubley, clubley at remove_me.eisner.decus.org-Earth.UFP
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